Johnny Cash has "probably four or five albums" worth of unheard material that could eventually be released, according to the country music legend's son.

In an interview with The Guardian, producer/songwriter John Carter Cash said there were "a few things that are in the works right now – probably four or five albums if we wanted to release everything."

John Carter Cash said a good chunk of that material stems from his father's recordings with Rick Rubin for his American Recordings label in the 1990s and 2000s.

"There may be three or four albums worth of American Recordings stuff," he said. "But some of it may never see the light of day."

Tuesday saw the release of "Out Among the Stars," a long-lost album Cash recorded with Billy Sherrill in the early '80s that was shelved by his then-label, Columbia Records. The master tapes were discovered in 2012.